Fig 3. Expansion in different organs of Exo1^+/+, Exo1^-/- and Exo1^A/A male mice.

Statistical analysis of the data shown in this figure is described in the Material and Methods section. A) The average number of repeats added to the PM allele in different organs of 5 Exo1^+/+, 5 Exo1^-/- and 4 Exo1^A/A 6-month-old male mice. The original inherited allele in each case had 172–179 repeats. The repeat number added represents the difference of the repeat size in the indicated organ relative to the repeat number in heart, an organ that shows no expansion and thus which reflects the size of the original inherited allele. The error bars indicate the standard deviation. The effect of genotype was only significant for testis and small intestine (p < 0.0001). In these organs, the within group differences i.e. the differences between expansions in Exo1^+/+ and Exo1^-/-, Exo1^+/+ and Exo1^A/A and Exo1^-/- and Exo1^A/A mice were all significant (p = 0.016). B) Representative repeat PCR profiles from the heart and testis of mice with the indicated Exo1 genotypes. C) Proportion of alleles that were larger than, smaller than and the same size as the parental alleles in the progeny of Exo1^+/+ and Exo1^A/A male mice 62 pups from 7 Exo1^+/+ and 35 pups from 6 Exo1^A/A males were analyzed (p = 0.04).